1. Field of the Invention
This invention relates, in general, to hydraulic couplings and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, the invention involves an undersea hydraulic coupling having a pressure energized Y-shaped metal seal that engages the face of the male member, the female member bore and an internal shoulder in the bore, to provide a radial seal and face seal between the coupling members.
2. Description of Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with seals to seal the junction between the male and female members. The female member generally has a cylindrical body with a relatively large diameter bore at one end and a relatively small diameter bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore contains the seals and receives the male portion of the coupling. The male member includes a probe section insertable into the large bore of the female member. According to various embodiments of the device, the seals either abut the end, or face, of the male member or engage the male member about its outer circumference. Hydraulic fluid is then free to flow through the female and male portions of the coupling and seals prevent that flow from escaping about the joints of the coupling.
A check valve may be installed in the female member and also in the male member. Each check valve is opened when the coupling is made up; however, each check valve closes when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is a part.
In U.S. Pat. Nos. 4,694,859 and 5,762,106 to Robert E. Smith, III, an undersea hydraulic coupling and radial metal seal is disclosed. A reusable metal seal engages the circumference of the probe when it is positioned within the female member body. The seal is held in place by a cylindrical body or retainer. When the male and female portions of the coupling are parted under pressure, the retainer prevents the metal seal from blowing out through the bore of the female member.
U.S. Pat. No. 4,637,470 to Gary G. Weathers et al discloses a subsea hydraulic coupling having a resilient metal sealing ring having two lips that face inwardly, defining a general V-shape. Belleville washers are used to maintain the male member face in sealing engagement with the sealing ring. Additionally, fluid pressure in the female member bore will tend to expand the lips of the seal ring to maintain a tight seal between the face of the male member and the shoulder in the female member bore.
U.S. Pat. No. 5,015,016 to Robert E. Smith, III discloses a subsea hydraulic coupling having an internal pressure loaded V-seal that engages the leading face of the male member and a sleeve inserted into the female member bore. The V-seal is preloaded to prevent leakage at low pressures. When the system is pressure energized, the sleeve member urges toward the male member to keep the V-seal engaged with the male member. The pressure causes the V-seal to expand longitudinally against the leading face of the male member and the internal shoulder of the sleeve member.
U.S. Pat. No. 5,355,909 to Robert E. Smith, III discloses an undersea hydraulic coupling having a pair of hollow metal seals which are pressure energized to seal between the male and female members of the coupling. One of the hollow metal seals is configured to expand radially while the second hollow metal seal is compressible along the longitudinal axis of the coupling. These seals provide a fluid tight sealing arrangement upon pressurization of the coupling without the need for external preload devices.
U.S. Pat. No. 5,979,499 to Robert E. Smith, III discloses an undersea hydraulic coupling having a ring-shaped metal seal that is held in place between the female member body and a sleeve-shaped seal retainer. The annular metal seal includes a lip or leg section which is clamped in place between the female member body and the seal retainer. A hollow portion of the seal extends radially inwardly from the lip portion of the seal and is expansible to form a fluid tight seal against the body of the male member. The hollow portion of the seal is preferably cylindrical in cross section.
U.S. Pat. No. 4,884,584 to Robert E. Smith, III discloses an internally preloaded metal-to-metal seal hydraulic coupling having a seal member that is allowed to float, or slide, longitudinally within the bore of the female coupling member between a first, extended position and a second, compressed position. The seal member is biased by a preload mechanism into its first extended position. A force resulting from engagement of the male member and the seal member tends to urge the seal member towards its second, compressed position and that force is opposed by the preloaded mechanism. An annular metal ring seal may be used to provide a sliding fluid seal between the outer circumference of the seal member and the bore of the female.
Some types of hydraulic couplings with face-type metal-to-metal seals require external preload devices for the seal. An external preload mechanism typically is used to prevent relative longitudinal movement between the male member and the female member and, as a result, disengagement of the seals. A problem with external preload devices is the devices must overcome the fluid pressure which may urge the members apart. The external device must not only partially energize a seal, but also overcome the hydraulic pressure which urges the members to separate. This is a serious problem particularly when high pressure is desired for hydraulic lines, and in such a case the hydraulic pressure may overcome the preload device and the sealing relationship may be lost.
The sealing relationship also may be lost in prior art couplings with face-type seals that do not employ external preload devices. This problem is caused by any relative longitudinal movement of the coupling members. Any longitudinal movement between the members can not be tolerated without sacrificing the sealing relationship.
While face-type seals have certain disadvantages in undersea hydraulic couplings, radial seals allow substantial separation of the coupling members. However, radial seals may require seal retaining devices and tolerances or dimensional irregularities may diminish the effectiveness of radial seals. It is desirable to enhance the effectiveness of the seal by designing an undersea hydraulic coupling that will allow some separation of the coupling members without the need for pre-load devices, and that assures the seal remains fully engaged between the male and female members. Thus, an undersea hydraulic coupling is needed having a face-type metal seal that tolerates substantial separation of the male and female members.